[112.01] The Clustering and Photometric Properties of Faint Galaxies

D. Woods (U. British Columbia)

A photometric survey of faint galaxies in three high
Galactic latitude fields is used to study the clustering
properties of the faint galaxy population, with two
approaches: close pair and angular correlation analysis.

The number of close pairs of galaxies observed to faint
magnitude limits, when compared to nearby samples,
determines the interaction or merger rate as a function
of redshift, which is fundamental for understanding galaxy
evolution. Using the deep imaging from one of the fields
pair fractions are determined which are consistent with the
galaxies in the sample being randomly distributed with no
significant excess of close pairs. This is contrary to
pair fractions found by other authors for similar magnitude
limits and using an identical approach to the pair analysis.

Angular correlation analysis is applied to magnitude-limited
and colour-selected samples of galaxies from the three
fields, for larger angular separations than those studied
with close pair analysis. General agreement is obtained
with other recent studies which show that the amplitude of
the angular correlation function (ømega(\theta)) is
smoothly decreasing as a function of the R limiting
magnitude. This decline of omega(\theta) rules out
the viability of merger-dominated galaxy evolution
models. Using redshift distributions extrapolated to
faint magnitude limits, galaxy clustering evolution models
are calculated and compared to the observed I-band
omega(\theta). Faint galaxies are determined to have
correlation lengths and clustering evolution parameters
of either r_0\sim4 h^-1 Mpc and \epsilon\sim0-1;
r_0\sim5-6 h^-1 Mpc and \epsilon>1; or
r_0\sim2-3 h^-1 Mpc and \epsilon\sim-1.2. The
first of the three cases has the most reasonable rate of
clustering evolution but distinguishing the correct
r_0 for the faint galaxies is not possible with the
current data. No significant variations in the clustering
amplitude as a function of colour are detected, for all
the colour-selected galaxy samples considered.